diff --git a/Tools/msi/dev/dev.wixproj b/Tools/msi/dev/dev.wixproj
index e144878a53c..682b66031f1 100644
--- a/Tools/msi/dev/dev.wixproj
+++ b/Tools/msi/dev/dev.wixproj
@@ -37,12 +37,12 @@
             Condition="$(BuildForRelease)">
         <!-- Build libpython##.a as part of this project. This requires gendef and dlltool on the path. -->
         <PropertyGroup>
-            <_GenDefPlatform>i386</_GenDefPlatform>
-            <_GenDefPlatform Condition="$(Platform) == 'x64'">i386:x86-64</_GenDefPlatform>
+            <_DllToolOpts>-m i386 --as-flags=--32</_DllToolOpts>
+            <_DllToolOpts Condition="$(Platform) == 'x64'">-m i386:x86-64</_DllToolOpts>
         </PropertyGroup>
 
         <Exec Command='gendef - "$(BuildPath)$(PyDllName).dll" &gt; "$(IntermediateOutputPath)mingwlib.def"' ContinueOnError="false" />
-        <Exec Command='dlltool --dllname $(PyDllName).dll --def "$(IntermediateOutputPath)mingwlib.def" --output-lib "$(BuildPath)lib$(PyDllName).a" -m $(_GenDefPlatform)' />
+        <Exec Command='dlltool --dllname $(PyDllName).dll --def "$(IntermediateOutputPath)mingwlib.def" --output-lib "$(BuildPath)lib$(PyDllName).a" $(_DllToolOpts)' />
     </Target>
 
     <Import Project="..\msi.targets" />